Vertical magnetic recording is a promising recording technology for recording magnetic data on a disk whose magnetic moment is perpendicular to the plane of the disk. The development from longitudinal magnetic recording to vertical magnetic recording will advance the increasing density of data on the disks in the future.
The magnetic head using the vertical recording method includes a thin film coil for generating magnetic flux and a magnetic pole layer extending from the rear portion of the air bearing surface and emitting the magnetic flux generated by the film coil to the recording medium. The magnetic pole layer includes, for example, a track width defining portion including a width (uniform width) defining a recording track width of the recording medium. The height of the track width defining portion of the magnetic pole layer is the height of the neck served as an important factor for measuring the recording performance of the magnetic head, which is defined from the front end of the track width defining portion to its trailing end. In the vertical recording method of the magnetic head, when the current flows through the thin film coil and the magnetic flux for recording is generated, the magnetic flux is emitted from the tip of the track width defining portion in the pole layer, thereby generating a recorded magnetic field (vertical magnetic field) for magnetizing the recording medium. Thus, the information is magnetically recorded on the recording medium. Recently, new magnetic heads have a function of not only recording information to a recording medium, but also a function of reading information from a recording medium.
Magnetic heads are typically constructed on a wafer that is sliced into separate row bars. One surface of the row bar will be lapped to obtain predetermined size for the read head portion and the write head portion, specifically, the MR height of the read head portion and the neck height of the write head portion are desirable, to form an air bearing surface. After that, the row bar will be cut into individual magnetic heads.
For ensuring the running performance of the film magnetic heads, it's necessary to maintain the high accuracy of the MR height for reading and the neck height for writing during the lapping process. The lapping process is commonly controlled by means of electrical lapping guides (ELG) formed on different positions of the row bar. Conventionally, the ELG is configured between two adjacent magnetic heads, while the current ELG may be directly configured on the magnetic head. In some samples, one magnetic head may be provided with one or more ELGs. While two ELG pads are formed on the surface of the magnetic head to connect with the ELGs, thus a resistance measure can be performed by means of the ELG pads. Resistance of the ELG will be varied as the lapped quantity, which may be used for monitoring the lapping process during the manufacturing of the magnetic head therefore. Once the resistance of the ELG is achieved to a threshold value, the lapping process is finished.
Commonly, a measurement device for measuring the resistance of ELG includes a probe board, multiple pins of the probe are in contact with the ELG pads on the row bar, and the pins are connected with the a measurement board to form a current loop on each magnetic head of the row bar, thereby measuring the resistance for each magnetic head. However, due to these ELG pads have planar surface, thus the probe contacting with the planar and smooth surface will be easily shifted and removed across the surface during the lapping process, which leads to an inaccurate measurement or even a failed measurement.
Hence, it is desired to provide an improved row bar and a wafer for forming magnetic heads to overcome the above-mentioned drawbacks.